Soft-sided luggage, especially duffel bags, has become popular because of its lightweight yet durable construction. Some soft-sided luggage is also collapsible for occupying less storage space when not in use. These can have fabric shells that are unframed (like most duffel bags) or are framed by assemblies that can be taken apart for collapsing the fabric shells.
For example, U.S. Pat. No. 5,178,245 to Cox discloses a suitcase shell reinforced by removable resilient loops. End compartments of the shell can be opened for removing the loops and collapsing the shell. U.S. Pat. No. 4,598,802 to Abenaim discloses a suitcase with a central band-like frame having a U-shaped base and two hinged arms. Two side walls can be detached from the frame, and the hinged arms can be disconnected and folded along with the side walls into the base.
The suitcases of both Cox and Abenaim require disassembly to collapse. For example, parts of their shells must be opened or removed to expose their frames, and their frames must be removed or dismantled to complete the collapse. Such disassembly is time consuming and, if done improperly, could damage the luggage. Subsequent reassembly has similar problems. Also, breakdown of the suitcase assemblies into parts adds possibilities for misplacing one or more parts, rendering the suitcase unusable.
Duffel bags ordinarily do not have frames and can be collapsed without significant resistance. However, such bags can be difficult to pack because they do not retain a fixed form. Small openings in duffel bags are difficult to access, and large openings allow contents to spill out.